Commonly, in the processing of fresh crab after it has been cleaned and cut into sections, the crab sections are loaded into heavy-duty galvanized-steel wire-mesh baskets which are then conveyed along an overhead track by carriage-mounted lifting winches to various processing stations for cooking and freezing. The baskets are then unloaded and the frozen modules of crab sections are packed in suitable fibreboard cartons.
The baskets were at one time made with large foldable rectangular sides, and had a wire grid top provided with a lifting eye and pawl type top lock mechanisms, so that when the basket was folded to the upright position and the lid placed on top, a lock-up would be completed. Generally the basket had two interior chambers, separated by a wire grid divider. The basket was generally made to the maximum practical size useable in the customer's processing tanks and became known as a bulk pack basket.
There was no attempt to equalize the weight of product in the bulk pack baskets. The principal focus was to jam as much crab into the baskets and through the processing system as possible. As time went by the bulk type basket was improved to include flow-through dividers,
The next step was the introduction of a double stack basket to facilitate handling and packing. This basket retained the same concepts as the bulk pack baskets except that it had added thereto a light angle iron base frame to permit stacking and add strength. This model resulted in the development of a lid lift yoke consisting of a lid whereon there was welded a lift backbone combined with two offset hinged wire arms that stored side-by-side on top of the lid. These arms were arranged to rotate downward 270 degrees and drop over contact pickup arrangements on each individual basket within the stack to lock the baskets as a unit for pickup on the overhead lifting mechanism to convey the stack unit through the processing system.
As time went by crab processors required various shapes and sizes of basket units. Use of horizontal double compartment baskets with flow through dividers began. These were combined with two stack and three stack modules. Then tapered baskets were introduced having all four sides tapered so that the baskets in a stack could be nested, the nesting being limited to a depth of about an inch by cleats on the baskets arranged to engage the upper rim of the next lower basket. Discharge of the frozen product from a tapered basket is usually achieved by either turning the basket over within a fibre carton, or providing the basket with an ejection bottom which comprises a loose grid in the bottom of the basket. The ejection bottom is elevated upward at an unloading station so that the block of frozen product is positioned on the elevated bottom above the top rim of the basket. The packing operator slips an upside-down fibre box over the product block and turns the box upright with the frozen product block inside.
At about the same time that the commercial use of tapered baskets commenced, the market began to require smaller modules of frozen product and more weight control. This in turn created a need to use smaller baskets in the processing system and to be able to increase the number of baskets contained in each processing module, as, for example, twelve baskets arranged in four stacks, without complicating loading and unloading of the baskets. Furthermore, there was a need to make the multi-basket module as compact as possible so that processing tank sizes could be kept to a minimum, and to do so without sacrificing structural strength and basket durability.